Method and apparatus for reducing drag on a vehicle in motion and channeling air flow to form a bug shield

ABSTRACT

A system for reducing turbulence and therefore improving fuel efficiency for land-operated vehicles uses at least one linear array of vortex generators along typically a leading edge of a vehicle profile. I addition an aerodynamic bug diversion system is provided for creating and directing an airflow shield to prevent bugs and other lightweight debris from hitting the windshield of a moving vehicle.

FIELD OF THE INVENTION

[0001] The present invention is in the field of reducing drag on landoperated vehicles, and pertains particularly to a system for channelingair to reduce frictional drag and to form a bug guard from the channeledand directed airflow.

BACKGROUND OF THE INVENTION

[0002] The art of aerodynamic design is one of continual change andimprovement. In addition to streamline profiling of surfaces belongingto aerodynamic vehicles of ground, air and water types, a number ofaerodynamic aids have been provided in the form of accessories that maybe attached to vehicles at strategic locations with the idea of reducingdrag on those vehicles. Air-foils of various designs are the mostrecognized of these products.

[0003] With respect to road transport vehicles such as semi tractortrailers and the like, the bluff profile inherent with such vehiclescauses more drag when moving through air than with streamlined profilesthat are not practical in production of such vehicles. Therefore, alarge market exists for ways to reduce drag on such bluff-bodiedvehicles to improve fuel use when the equipped vehicles are driven atcertain speeds.

[0004] Aerodynamic drag on bluff-bodied vehicles consists mainly ofpressure drag with skin friction created by moving air and base drag,which forms part of the total drag coefficient on the vehicle. Air-flowover bluff bodies comprises large wake production and smaller vortexshedding. The well-known Reynolds number associated with drag on smalland medium vehicles falls in the sub-critical range of (1.0 to 2.0×10⁶).Total drag force associated with such typical flow patterns is veryhigh. A considerable amount of energy is therefore expended inovercoming such forces.

[0005] Streamlining vehicle designs is one of the most popular knownmethods for reducing aerodynamic drag. The effectiveness of roundingcorners in design can be measured by utilizing a simple two-dimensionalsquare section under test. The drag coefficient on such a square sectionat sub-critical Reynolds numbers is approximately 2.0. Maximally roundedcorners improve the coefficient to a limiting factor of approximately1.0 or a 50% reduction in drag without major design change.

[0006] Small vortex generators are known in the art, and are used intypically small aircraft to increase lift. Referring now to FIG. 1 ofthis specification, a vortex generator is illustrated in perspectiveview. Generator 100 has a base portion 101 that makes contact with thesurface of a vehicle to which it is mounted and a fin portion 102 formedat a substantially upright direction from the base of the unit.

[0007] Typically, an array of such generators are arranged on aleading-edge surface of an aircraft wing to increase lift. Referring nowto FIGS. 2a, 2 b, and 2 c, the generator of FIG. 1 is illustrated inTop, Side, and End views to better show construction. In FIGS. 2a and 2c, part of fin 102 is shown removed along an angle D for the purpose offurther drag reduction in the design. Dimensions B (FIG. 2a), C (FIG.2b) and E (FIG. 2c) can vary according to application.

[0008] An object of the present invention is to reduce drag and toincrease fuel efficiency of a bluff-body vehicle through strategicalignment and positioning of vortex generators at leading edges of thevehicle. A further object of the present invention is to use the laminarflow enhanced by added vortex generators to circumvent a common problemof bug collision with windshields of such vehicles while traveling atfreeway speeds.

SUMMARY OF THE INVENTION

[0009] In a preferred embodiment of the present invention an aerodynamicbug diversion system for creating and directing an airflow shield toprevent bugs and other lightweight debris from hitting the windshield ofa moving lo vehicle is provided, comprising an array of vortexgenerators affixed in a line substantially at a right angle to thedirection of vehicle travel at a leading edge of the vehicle forcreating a channeled and uniform laminar airflow, and an airfoil havingat least 2 foils held spaced apart and substantially parallel to oneanother for collecting and redirecting the airflow created by the vortexarray. The system is characterized in that the airflow through theairfoil is redirected as a substantially flat and uniform flow travelingupward in a plane substantially parallel to the plane of the windshieldproviding a divertive shield against bugs and debris hitting thewindshield.

[0010] In some embodiments the airfoil is formed of one polymer piece ina molding operation. In other embodiments the airfoil may be formed of 2or more polymer pieces and is assembled. In some cases the at least twofoils are held spaced apart by a plurality of support fins, the finsaiding in channeling the air flow. Various materials can be used, suchas aluminum.

[0011] In some embodiments the airfoil can be adjustable to a specificprofile, adjusting one or both of the spacing and the direction..

[0012] In another aspect of the invention an airfoil for directing anairflow shield to prevent bugs and other lightweight debris from hittingthe windshield of a moving vehicle, comprising a base foil having aforward protruding lip for collecting incoming airflow and an uprightcurvature substantially following the angle of protrusion of thewindshield from the vehicle, and an upper foil connected to andspaced-apart from the base foil at a position elevated from andsubstantially parallel to the base foil. The airfoil is characterized inthat the space between the base foil and the upper foil functions toredirect airflow in a path substantially parallel to the windshield,forming a bug shield of moving air.

[0013] In some cases the upper foil is held rigidly above the base foilby a plurality of support fins, the fins aiding in channeling theairflow. The apparatus can be formed of one polymer piece in a moldingoperation, of two or more pieces. Various materials can be used, such asaluminum. The airfoil may be adjustable in one or both of directionand/or spacing. Further, there may be two or windshield support feetadapted as standoffs to the windshield.

[0014] In another aspect of the invention a method for preventing bugsand other lightweight debris from hitting the windshield of a vehicle isprovided, comprising steps of (a) collecting an incoming airflow in anairfoil having at least an upper foil and a base foil while the vehicleis in motion; and (b) redirecting the captured airflow through theairfoil in an upward direction substantially parallel to the windshield.

[0015] In some embodiments, in step (a), the incoming airflow ischanneled, prior to the airfoil, through an array of vortex generators.The airfoil may be a contiguous piece formed in a molding operation, ormay be made of two or more pieces that are assembled together.

[0016] In some cases the airfoil is adjustable in one or both of spacingand direction. Also in some cases the foils comprising the airfoil areheld apart by a plurality of support fins, the fins aiding in channelingthe air flow created by the vortex array. Redirection in preferredembodiments is accomplished through curvatures formed in the airfoil.

[0017] In yet another aspect of the invention a system for reducing dragon a land-operating vehicle, and therefore increasing fuel efficiency isprovided, comprising an array of vortex generators, each presenting asubstantially vertical foil to an airstream created by driving thevehicle through ambient air, the array affixed to a surface of thevehicle and extending substantially in a line at a right angle to thedirection of vehicle travel, the system reducing turbulence andenhancing laminar flow.

[0018] In some embodiments the line of generators is imposed along aforward position on a hood of the vehicle. In other embodiments the lineof generators is imposed along a forward position on a cab top of thevehicle. In yet other embodiments a first line of generators imposedalong a forward position on a cab top of the vehicle, and a second lineof generators along a forward position of a hood of the vehicle. Theindividual generators may be aligned to spread the laminar flow createdto a width greater than the width of the line of generators.

[0019] In embodiments of the invention taught below in enabling detail,for the first time a system is provided wherein vortex generators areused to reduce drag and thusly lower operating costs for land vehicles,such as trucks and buses. In addition, a system is provided thateliminates bug impingement on windshields of such vehicles, and the bugsystem can be used with the vortex generators as well.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0020]FIG. 1 is a perspective view of a vortex generator according toprior art.

[0021]FIG. 2A is an overhead view of the generator device of FIG. 1.

[0022]FIG. 2B is an elevation view of the generator device of FIG. 1.

[0023]FIG. 2C is and end view of the generator device of FIG. 1.

[0024]FIG. 3 is a front elevation view of an array of the vortexgenerators of FIG. 1 mounted to a land vehicle according to anembodiment of the present invention.

[0025]FIG. 4 is a front view of a bug foil apparatus according to anembodiment of the present invention.

[0026]FIG. 5 is a section view illustrating the elevation profile of thebug foil apparatus of FIG. 4.

[0027]FIG. 6 is a diagram illustrating airflow through the array ofvortex generators of FIG. 3 into the bug foil apparatus of FIG. 4producing bug-divertive effects.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The inventor provides a system for channeling air using vortexgenerators and techniques, and also directing the channeled air in a wayto eliminate bug collision with a windshield of a bluff-body vehicle.

[0029]FIG. 3 is a front elevation view of an array of vortex generators100 of FIG. 1 and a bug foil apparatus mounted to a vehicle according toan embodiment of the present invention. A tractor of a semitractor-trailer style truck is illustrated in this example as abluff-bodied vehicle that would benefit from the system of the presentinvention. An array of vortex generators 100 is mounted to theleading-edge surface of truck 300, along the front of the hood. Aparticular arrangement of the generators is provided such that thegenerators direct the air flow to fan out to the breadth of thewindshield of truck 300. This is accomplished by angling generators 100in the array applied to the truck hood. In addition the laminar flowlayer created is directed to enter a forward scoop provided on a bugfoil apparatus 301. The actual angle of mounting for generators 100 inthe illustrated array may vary according to the application. The angleis exaggerated in this example for illustrative purpose only. A 30 to 35degree offset from a 90-degree axis is about right for most truckapplications. As can be seen in this view, there are fourteen generatorstotal in the array. One or more vertically aligned generators (notshown) can be inserted into the array at center without departing fromthe spirit and scope of the invention and without reducing efficiency ofthe array in reducing drag.

[0030] Bug foil apparatus 301 is aerodynamically designed to receive themostly laminar air flow layer created by the generators and to redirectthe air flow in a direction substantially parallel to the windshield tocause, in effect, a fast moving and uniform layer of air functioning asa shield against bug collision.

[0031] Bug foil apparatus 301 in one embodiment is formed of onecontiguous piece of durable polymer such as would be the case forinjection molding. In another embodiment, foil 301 is molded in two ormore pieces, particularly an upper foil and a lower foil that may beassembled together. Bug foil apparatus 301 may be side mounted to truck300 using conventional mounting hardware (not shown). In anotherembodiment foil 301 may be secured to the vehicle surface immediatelyadjacent to the rearward boundary of the hood element so as not tointerfere with normal raising and lowering of the vehicles hoodapparatus. In a preferred embodiment foil 301 has 2 foils spaced apartand joined together in a substantially parallel configuration (one atopthe other) by a plurality of support fins (not visible in this example).The space created between the two foils acts to redirect the fastmoving, mostly laminar air layer from the vehicle hood in a directionupwards and parallel with the windshield approximately in the directionof the arrows illustrated.

[0032] The benefit of cooperation between generators 100 and foil 301 isthat the re-directed air flow is substantially flat, laminar, and fastmoving against the windshield providing an effective barrier againstbugs presented in the line of the windshield while truck 300 is movingat freeway speeds. Bug foil 301 stands off of the windshield of truck300 in such a way as to clear the windshield wiper apparatus and allowit to operate unimpeded, and to avoid turbulence that would otherwise becreated.

[0033] A second array of vortex generators 100 is strategically locatedimmediately above the windshield of truck 300 in substantially the sameangle of placement as the first-mentioned array. This particular arrayis not operative in the system of foil 301, but is provided simply forfurther vortex generation and drag reduction at the position at the topof the cab of the truck 300.

[0034]FIG. 4 is a front elevation view of bug foil 301 according to anembodiment of the present invention. Foil 301 comprises 2 main foils. Afoil 303 is provided as a base foil and a foil 302 is provided as anupper foil in the assembly. Base foil 301 is formed with an elongatedlip spanning the width of foil 301 and curved generally to adapt to thecurve of a windshield where the windshield abuts the vehicle dash frame.The exact amount of elongation and curve depends on the curvature of thewindshield and angle of protrusion of the windshield above the vehicleas generally viewed from the side of the vehicle. Base foil 303 restsdirectly on the vehicle surface behind the hinge location of the vehiclehood so that no air enters beneath base foil 303 in operation. Theelongated portion of base foil 303 acts primarily as a scoop forcapturing the fast moving air layer created by vortex generators (100)described above with reference to FIG. 3.

[0035] Foil 302 is held in an elevated and substantially parallelposition from base foil 303 by a plurality of standoff fins 304distributed strategically along the width of foil 301. Fins 304 help tochannel the air much in the same way as the vortex generators. Fins 304are disposed at slight angles in between base foil 303 and upper foil302 to help direct the airflow in a strategic fashion as to spread theflow evenly over the windshield. As seen in this view, the fins disposedleft of center are angled slightly to the left and the fins disposed tothe right of center are angled slightly to the right. 30 to 35 degreesdivergence of 90 degrees is sufficient for the purpose.

[0036] Foil 301 has at least 5 windshield support feet 306 formedthereon at strategic locations on the underside of base foil 303.Support feet 306 are formed-generally in the same shape as standoff fins304. Foil 301 is held in an elevated position above standard windshieldwiper apparatus by support feet 306. Feet 306 are positioned just out ofoperating reach of the windshield wiper assembly in operation. In thisexample there are five feet 306, two on either side of foil 301 and onesituated at center, but in many embodiments there are two supports ateach of the outboard ends, as many wiper patterns overlap, and a centersupport still can be used. In this way foil 301 is held above the wiperassembly and is held rigid so that it does not flex considerably underwind pressure. Moreover, wind pressure against base foil 303 acts tourge the foil to its mating surface preventing any air from enteringunderneath. This configuration also acts to prevent typical airflowturbulence and significant drag from occurring against the wiperassembly on a normal vehicle in motion and protects the wiper assemblyfrom bugs and other debris.

[0037]FIG. 5 is a section view illustrating an elevation profile of bugfoil 301 of FIG. 4. Bug foil 301 is curved for airflow redirectionaccording to a preferred embodiment of the present invention. Base foil303 is flush against the vehicle hood at its forward position redirectsair into the foil channels formed of the space between foil 303 and foil302 set apart by support fins 304. In one embodiment of the presentinvention, an adjustment mechanism (not shown) may be provided toproperly adjust the side profile of foil 301 to the angle of protrusionof the windshield above the hood of the vehicle. Such a mechanism couldbe incorporated in an embodiment where foils 302 and 303 are disposed onan axle that is rotatable and directly controlled by such as a turn knobdisposed at either or both ends of the foil. In this case, windshieldfeet 306 would also be adjustable and a separable part of the assembly.

[0038] In this example, bug foil 301 is rigid and is manufactured withthe appropriate curve. In still another embodiment, shims may be usedunder feet 306 to adjust the elevation angle of foil 301. There are manypossibilities that do not depart from the spirit and scope of theinvention. As can be seen in this example, the tail ends at some lengthof both foils 303 and 302 lie in a substantially parallel plane with theangle of windshield 306, but in a state of elevation above thewindshield.

[0039]FIG. 6 is a use diagram illustrating airflow through a leadingarray of vortex generators of FIG. 3 into the bug foil of FIG. 4producing bug-shielding effects. In this view, airflow against the bodyline at the start of the hood is channeled by an array of vortexgenerators 100 analogous to the array 100 described with reference tothe example of FIG. 3 above. In this and other applications theundersurface of the vortex generators may be curved to facilitatemounting on the vehicle body.

[0040] The air becomes streamlined and turbulence is prevented along thehood line. The laminar flow has a much lower drag coefficient thanturbulent flow, and creates less drag on the vehicle, thereforedecreasing overall drag and improving fuel efficiency.

[0041] At the back of the hood the laminar air flow is directed into thescoop formed by the base and upper foil of bug foil 301. At this pointthe air flow is re-directed into the direction parallel to the surfaceof the windshield. In some cases the spacing is adjusted to acceleratethe air flow as well. At normal freeway driving speeds the density andvelocity of the laminar flow parallel to the windshield is sufficient toprevent any bugs or other lightweight debris from coming into contactwith the windshield. Debris and bugs are captured in the air flow anddiverted upward parallel to the windshield, and do not come into contactwith the windshield.

[0042] In tests with no bug foil windshields are shown to be coveredwith smashed bugs. With the bug foil in an embodiment of the invention,at moderate highway speed, a lower portion of the windshield is bug-freeup to a distinct line, and bugs decorate the windshield above that line.As speed is increased, the line is elevated until, at some speed, nobugs impinge on the windshield. Adjustment of length and spacing of thefoils effects the speed at which the windshield becomes bug-free.

[0043] One with skill in the art of aerodynamics will recognize thesignificance of the uniform airflow traveling at high velocity parallelto the windshield as an effective bug deflecting mechanism.

[0044] In view of the many embodiments presented herein and thosepossible without departing from the spirit and scope of the inventionbut not specifically described, the present invention should be affordedthe broadest possible scope under examination. Only the claim languagethat follows should limit the spirit and scope of the invention.

What is claimed is:
 1. An aerodynamic bug diversion system for creatingand directing an airflow shield to prevent bugs and other lightweightdebris from hitting the windshield of a moving vehicle comprising: anarray of vortex generators affixed in a line substantially at a rightangle to the direction of vehicle travel at a leading edge of thevehicle for creating a channeled and uniform laminar airflow; and anairfoil having at least 2 foils held spaced apart and substantiallyparallel to one another for collecting and redirecting the airflowcreated by the vortex array; characterized in that the airflow throughthe airfoil is redirected as a substantially flat and uniform flowtraveling upward in a plane substantially parallel to the plane of thewindshield providing a divertive shield against bugs and debris hittingthe windshield.
 2. The bug diversion system of claim 1 wherein theairfoil is formed of one polymer piece in a molding operation.
 3. Thebug diversion system of claim 1 wherein the airfoil is formed of 2 ormore polymer pieces and is assembled.
 4. The bug diversion system ofclaim 1 wherein the at least two foils are held spaced apart by aplurality of support fins, the fins aiding in channeling the air flow.5. The bug diversion system of claim 1 wherein the airfoil is formed ofaluminum.
 6. The bug diversion system of claim 1 wherein the airfoil isadjustable to a specific profile, adjusting one or both of the spacingand the direction.
 7. An airfoil for directing an airflow shield toprevent bugs and other lightweight debris from hitting the windshield ofa moving vehicle comprising: a base foil having a forward protruding lipfor collecting incoming airflow and an upright curvature substantiallyfollowing the angle of protrusion of the windshield from the vehicle;and an upper foil connected to and spaced-apart from the base foil at aposition elevated from and substantially parallel to the base foil;characterized in that the space between the base foil and the upper foilfunctions to redirect airflow in a path substantially parallel to thewindshield, forming a bug shield of moving air.
 8. The airfoil of claim7 wherein the upper foil is held rigidly above the base foil by aplurality of support fins, the fins aiding in channeling the airflow. 9.The airfoil of claim 7 wherein the airfoil is formed of one polymerpiece in a molding operation.
 10. The airfoil of claim 7 wherein theairfoil is formed of 2 or more polymer pieces and is assembled.
 11. Theairfoil of claim 7 wherein the airfoil is formed of aluminum.
 12. Theairfoil of claim 7 wherein the airfoil is adjustable in one or both ofdirection and/or spacing.
 13. The airfoil of claim 7 wherein the basefoil has at least two windshield support feet adapted as standoffs tothe windshield.
 14. A method for preventing bugs and other lightweightdebris from hitting the windshield of a vehicle comprising steps of: (a)collecting an incoming airflow in an airfoil having at least an upperfoil and a base foil while the vehicle is in motion; and (b) redirectingthe captured airflow through the airfoil in an upward directionsubstantially parallel to the windshield.
 15. The method of claim 14wherein in step (a) the incoming airflow is channeled, prior to theairfoil, through an array of vortex generators.
 16. The method of claim14 wherein in step (a) the airfoil is a contiguous piece formed in amolding operation.
 17. The method of claim 14 wherein in step (a) theairfoil is formed of 2 or more pieces that are assembled together. 18.The method of claim 14 wherein in step (a) the airfoil is adjustable inone or both of spacing and direction.
 19. The method of claim 15 whereinin step (a) the foils comprising the airfoil are held apart by aplurality of support fins, the fins aiding in channeling the air flowcreated by the vortex array.
 20. The method of claim 14 wherein in step(b) redirection is accomplished through curvatures formed in theairfoil.
 21. A system for reducing drag on a land-operating vehicle, andtherefore increasing fuel efficiency, comprising an array of vortexgenerators, each presenting a substantially vertical foil to anairstream created by driving the vehicle through ambient air, the arrayaffixed to a surface of the vehicle and extending substantially in aline at a right angle to the direction of vehicle travel, the systemreducing turbulence and enhancing laminar flow.
 22. The system of claim21 wherein the line of generators is imposed along a forward position ona hood of the vehicle.
 23. The system of claim 21 wherein the line ofgenerators is imposed along a forward position on a cab top of thevehicle.
 24. The system of claim 21 using two lines of generators, afirst line of generators imposed along a forward position on a cab topof the vehicle, and a second line of generators along a forward positionof a hood of the vehicle
 25. The system of claim 21 wherein individualgenerators are aligned to spread the laminar flow created to a widthgreater than the width of the line of generators.